function r = f3(x0,s)

    x = [];
    y = [];

	
    for i = 1 :s 
        x = [x,(i-1)/(s-1)];
        y = [y,f(x)];
    endfor

    z = linspace(0,z,100) 
	
    w = lagrange(x,y,z);
    
    r = polival(z,w,x0)	
    
endfunction


